I'm working on the sitemaps of a multilingual website and I have a doubt regarding the best practice for referencing each language version of a page.
For a bit of background, the website references around 20 000 places with comments from the community and descriptions. The website is available in 5 languages (website.com/fr; website.com/it...)
For the moment, my sitemap only references english pages and in the sitemap for each page I specify
<xhtml:link rel="alternate" hreflang="en" href="URL"/> for each language (as well as English) as Google recommends.
In the Google Search Console, I see that about 75% of the pages with valid coverage are described as "indexed, not submitted in Sitemap" which makes me think that the alternate link with hreflang attribute is not enough to "submit" the page for google to index it.
Do I need to list the pages in all 5 languages in my sitemap and use as well
<xhtml:link rel="alternate" hreflang="en"... on each link?